Inside Julianne Hough's Relationship With Her Sister-In-Law Hayley Erbert

Julianne and Derek Hough's sibling bond continues to captivate "Dancing With the Stars" fans, but Derek's marriage to Hayley Erbert altered the brother-sister duo's dynamic (in the best way, of course). At age 11 and 13, respectively, Julianne and Derek left their family behind to study dance together in London, so they've been each other's main support system forever. As such, Julianne has been an important part of Derek's life in almost every way. When Derek married Erbert in August 2023, his little sister was in the wedding as a bridesmaid.

Julianne could hardly contain her happy tears when Derek and Erbert exchanged vows — a moment she deemed her favorite. "It was really special, really beautiful and so intimate and it felt like we were observing a private moment and that was just really beautiful," Julianne told Access that September. Julianne has known Erbert for as long as Derek, as the couple met when the brother and sister hired Erbert to take part on their "Move Live on Tour 2014," a year before they started dating. 

In 2015, Erbert joined "Dancing With the Stars," where she worked not only with her then-boyfriend, but also her future sister-in-law. Since then, the trio has worked together on several occasions. In 2020, Julianne, Derek, and Erbert were featured on "The Disney Family Singalong," dancing to "Mary Poppins" and "Beauty and the Beast." Working together is no guarantee of a close relationship, as plenty of co-workers dislike each other. Luckily for Julianne and Erbert, that doesn't seem to be the case. 

Julianne Hough has nothing but love for Derek Hough's wife. When Hayley Erbert had to undergo surgery to repair a cranial hematoma after suffering a burst blood vessel on December 6, 2023, her sister-in-law showed how worried she was. "Please pray and send all your love, healing and light to Hayley and Derek," Julianne wrote in an Instagram Story on December 8. A few weeks later, Julianne penned a heartfelt Instagram post about how she was feeling ahead of Christmas.

"Holding my family extra tight this holiday season," Julianne captioned a carousel of photos that featured different family members, including one in which she and Erbert shared an embrace (seen above). Ahead of Derek and Erbert's wedding, a source shared Julianne couldn't wait to be a witness to their love story. "Julianne is so excited she's finally going to be able to officially welcome Hayley into the family and call her a sister," the insider told Hollywood Life in June 2022.

Julianne never doubted Erbert was the perfect match for her brother. "Julianne has never seen Derek so happy with somebody before and she can't wait to see them take this next step in their relationship," the source added. Julianne and Erbert have also been bonding over their shared love for dancing for years. In 2018, Julianne shared a snap of them practicing together, giving insight into the nature of their relationship. "Hayley Erbert looking at me like I'm crazy," she laughed in a Facebook post.

Hayley Erbert thankfully made a full recovery after her emergency craniectomy and subsequent cranioplasty. But the life-threatening experience deeply affected her and Derek Hough's lives. "To this day, I still have really good days and I have really bad days — emotionally and physically sometimes — but I'm doing so much better every single day," Erbert said in a Instagram video shot alongside Derek in February, two months after the procedures. Erbert's recovery journey has filled her husband with pride. "She's unbelievable," Derek told Entertainment Tonight, also in February.

While Derek has always admired Erbert, the experience gave him a new perspective on her resilience. "When I married her, I knew she was strong, but I really didn't realize how strong she really was until now," he told the outlet. But Derek isn't the only one who seems to be in awe of Erbert following her journey. On New Year's Eve, Julianne showed she is equally proud of her sister-in-law with a comment left on an Instagram post in which Erbert reflected on the year she was leaving behind.

"You give a whole new meaning to 'I Lived' — what a beautiful year but an even more stunning life ahead! So grateful to be your sister," Julianne commented. Julianne also showed support for Erbert's new look, as she had to shave her head because of the surgeries. "Love you both! Also the most French chic hair ever," Julianne commented on Erbert and Derek's February video.